Individual package of absorbent article, wrapping sheet, and method of manufacturing wrapping sheet

ABSTRACT

Disclosed is a wrapping sheet for an absorbent article including an absorbent exhibiting at least a fluid-retaining property, the wrapping sheet includes: a first fiber layer formed by application of a high-pressure water jetting treatment, the first fiber layer including pulp fiber and chemical fiber, the pulp fiber content of the first fiber layer being 30% by mass to 70% by mass, the chemical fiber content of the first fiber layer being 70% by mass to 30% by mass, and the average fiber length of the chemical fiber being 20 mm or less; and a second fiber layer arranged by laminating the second fiber layer to the first fiber layer, the pulp fiber content of the second fiber layer being 70% by mass to 100% by mass.

TECHNICAL FIELD

The present invention relates to an individual package of an absorbentmaterial, a wrapping sheet used for the individual package, and a methodof manufacturing the same.

BACKGROUND ART

Absorbent articles such as sanitary napkins, pantiliners and disposableinterlabial pads are each wrapped with an individual wrapping material,which is prepared separately from the absorbent article, for sanitaryreasons and for portability reasons. In recent years, absorbent articleswith a hydrolytic property (or water degradability) which allows theabsorbent articles to be quickly dispersed by a large amount of waterhave been developed. When such an absorbent article is discarded into atoilet bowl after being used, the absorbent article can be dissolved inthe septic tank or the like in a short time without clogging a drainagepipe of the toilet. This leads to reductions of manpower and costsneeded for garbage collection and disposal.

Users wear absorbent articles mostly in toilets because of the nature ofthe absorbent articles. For this reason, it is desired that individualwrapping materials with which the absorbent articles are individuallywrapped should be also water-degradable. When individual wrappingmaterials are not water-degradable, users may sometimes feelinconvenience in disposal of the individual wrapping materials afterusing the absorbent articles.

With this taken into consideration, for example, paper of a type whichis softened through a crepe process for making the paperwater-degradable, and which has a basis weight of 20 g/m² to 40 g/m²,are used as wrapping materials for absorbent articles.

In addition, Japanese Patent Application Publications Nos. Hei 9-228214and 2001-172850 propose a water-degradable type of fiber sheet with ahigh wet strength and a good hydrolytic property, which is produced byapplying a high-pressure water jetting treatment to a fiber sheet formedby blending predetermined fibers.

-   Patent Document 1: JP-A 9-228214-   Patent Document 2: JP-A 2001-172850

A general type of paper exhibits a poor wet strength although it hasgood air tightness and hydrolytic properties. However, the general typeof paper is easily broken once it becomes wet when touched by a wethand, or when splashed with water. As a result, a problem with thegeneral type of paper is that it does not function as wrapping material.

In addition, the water-degradable type of fiber sheets with a hydrolyticproperty, which are disclosed by JP-A 9-228214 and 2001-172850, exhibitsflexibility and appropriate degree of wet strength with hydrolyticproperty. However, the water-degradable type of fiber sheets exhibit adegraded air tightness property in comparison with the general type ofpaper. This is because the formation of the water-degradable type offiber sheets is disturbed or fine pores are made in the water-degradabletype of fiber sheets, when a high-pressure water jetting treatment isapplied to the water-degradable type of fiber sheets. As a result, aproblem with the water-degradable type of fiber sheets is that, whenused as an individual wrapping material, the water-degradable type offiber sheets allow foreign matters such as dust to go in beyond thewater-degradable type of fiber sheets.

The present invention has been made for the purpose of solving theforegoing problems. An object of the present invention is to provide: anindividual package for an absorbent article, the individual packageexhibiting a hydrolytic property which allows the individual package tobe easily dispersed by water flow; a wrapping material and a wrappingsheet which both exhibits a hydrolytic property; and a method ofmanufacturing the same.

DISCLOSURE OF THE INVENTION

The inventors found that a wrapping sheet which reconciles a highhermetic property with a hydrolytic property can be provided in the formof a fiber sheet obtained by laminating two or more layers including afiber layer with an enhanced hermetic property and a fiber layer with anenhanced soft tactile impression, strength and the like. Thus, theinventors have completed the present invention. Specifically, thepresent invention provides the following things.

(1) A wrapping sheet for an absorbent article including at least anabsorbent exhibiting a fluid-retention property, including: a firstfiber layer formed by application of a high-pressure water jettingtreatment, the first fiber layer including pulp fiber and chemicalfiber, a pulp fiber content of the first fiber layer being 30% by massto 70% by mass, a chemical fiber content of the first fiber layer being70% by mass and 30% by mass, an average fiber length of the chemicalfiber being not more than 20 mm; and a second fiber layer arranged bylaminating the second fiber layer to the first fiber layer, the secondfiber layer including pulp fiber, the pulp fiber content of the secondfiber layer being 70% by mass to 100% by mass.(2) The wrapping sheet as recited in (1), in which the second fiberlayer includes chemical fiber, the second fiber layer includes chemicalfiber hot more than 30% by mass with an average fiber length of 20 mm orless and with a fiber diameter smaller than that of the pulp fiber.(3) The wrapping sheet as recited in any one of (1) and (2), furtherincluding a third fiber layer formed by application of a high-pressurewater jetting treatment and arranged by laminating the third fiber layerto one side of the second fiber layer with the first fiber layerlaminated to the other side of the second fiber layer, the third fiberlayer including pulp fiber and chemical fiber, a pulp fiber content ofthe third fiber layer being 30% by mass to 70% by mass, a chemical fibercontent of the third fiber layer being 70% by mass to 30% by mass, anaverage fiber length of the chemical fiber being not more than 20 mm.(4) The wrapping sheet as recited in any one of (1) to (3), in which,when a 10 cm×10 cm sample piece of wrapping sheet placed in 800 cc ofdistilled water is shaken at a shaking speed of 240 rpm for 30 minutes,the sample piece is so dispersed in the distilled water that the largestremaining piece of wrapping sheet is 50 cm² or less in size.(5) The wrapping sheet as recited in any one of (1) to (4), in which:the basis weight of the first fiber layer is 10 g/m² to 30 g/m²; thebasis weight of the second fiber layer is 15 g/m² to 30 g/m²; and thebasis weight of the wrapping sheet is 25 g/m² to 60 g/m².(6) The wrapping sheet as recited in any one of (3) and (4), in which:the basis weight of the first fiber layer is 10 g/m² to 30 g/m²; thebasis weight of the second fiber layer is 15 g/m² to 30 g/m²; the basisweight of the third fiber layer is 10 g/m² to 30 g/m²; and the basisweight of the wrapping sheet is 35 g/m² to 60 g/m².(7) The wrapping sheet as recited in any one of (1) to (6), in which apattern is formed in the first fiber layer and/or the second fiber layerby changing the basis weight of the first fiber layer and/or secondfiber layer.(8) The wrapping sheet as recited in any one of (1) to (7), in which thefirst fiber layer and/or the second fiber layer are colored.(9) The wrapping sheet as recited in (8), in which the color in whichthe first fiber layer is colored is different from color in which thesecond fiber layer is colored.(10) The wrapping sheet as recited in any one of (1) to (9), in which atleast one of the first fiber layer to the three fiber layer includes asizing agent, and at least partially exhibits a predetermined waterresisting property(11) An individual package of an absorbent article, including: anabsorbent article including at least an absorbent exhibiting afluid-retention property; and a wrapping material wrapping the absorbentarticle, the wrapping material constituted of the wrapping sheet asrecited in any one of claims (1) to (10).(12) A method of manufacturing a wrapping sheet, including the steps of:forming a first fiber layer from pulp fiber and chemical fiber into afiber web in a wet paper-forming method, and subsequently by applying ahigh-pressure water jetting treatment to at least one side of the fiberweb to entangle the pulp fiber and the chemical fiber with each other;forming second fiber layer from pulp fiber and chemical fiber; andconveying the first fiber layer, subsequently integrally laminating thefirst fiber layer and the second fiber layer to each other while thesecond fiber layer remains wet, thereafter drying the laminated firstand second fiber layers.(13) The method of manufacturing a wrapping sheet as recited in (12),further including the steps of: forming a third fiber layer from pulpfiber and chemical fiber into a fiber web in a wet paper-forming method,and subsequently by applying a high-pressure water jetting treatment toat least one side of the fiber web to entangle the pulp fiber and thechemical fiber with each other; and conveying the first fiber layer andthe second fiber layers after integrally laminating the first and secondfiber layers to each other while the first and second fiber layersremain wet, subsequently integrally laminating the third fiber layeronto the first and second fiber layers while the third fiber layerremains wet, thereafter drying the laminated first to third fiberlayers.(14) The method of manufacturing a wrapping sheet as recited in any oneof (12) and (13), in which, in at least one of the step of forming thefirst fiber layer and the step of forming the third fiber layer, thefiber web is transferred from a fiber layer forming wire to a patterningwire after the fiber web is formed, and subsequently the high-pressurewater jetting treatment is applied to the fiber web thus transferred.(15) The method of manufacturing a wrapping sheet as recited in any oneof (12) to (14), in which, for at least one of the first and third fiberlayers, the fiber web is formed by a paper-forming method of anyone of atanmo type and a fourdrinier type.(16) The method of manufacturing a wrapping sheet as recited in any oneof (12), (13) and (15), in which the high-pressure water jettingtreatment is applied to the fiber web placed on the fiber layer formingwire.(17) The method of manufacturing a wrapping sheet as recited in any oneof (12) to (16), in which, for the second fiber layer, the fiber web isformed by paper-forming method of any one of a cylinder type and aformer type.

According to the present invention, it becomes possible to provide anindividual package and a wrapping sheet which both exhibit a hydrolyticproperty, a soft tactile impression and appearance, and a high airtightness property which does not allow foreign matters to go in beyondthe individual package and the wrapping sheet.

In addition, the present invention employs a wet paper-forming andlayer-combining process with a paper machine to manufacture wrappingsheets with a laminated structure. Thus, it makes a secondary processunnecessary, and it achieves cost reduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of a wrapping sheetaccording to the present invention.

FIG. 2 is a perspective view of a second embodiment of the wrappingsheet according to the present invention.

FIG. 3 is a plan view showing a first embodiment of an individuallywrapped article according to the present invention.

FIG. 4( a) and FIG. 4( b) is a perspective view showing the firstembodiment of the individually wrapped article according to the presentinvention.

FIG. 5 is a perspective view of an interlabial pad

FIG. 6( a) and FIG. 6( b) is a perspective view of a second embodimentof the individually wrapped article according to the present invention.

FIG. 7 is a schematic view showing a method of manufacturing a wrappingsheet according to the first embodiment of the present invention.

FIG. 8 is a schematic view showing a method of manufacturing a wrappingsheet according to the second embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

A wrapping sheet according to the present invention is for wrapping anabsorbent article including at least an absorbent having a liquidretention property. The wrapping sheet is characterized by including afirst fiber layer and a second fiber layer. The first fiber layerincludes pulp fiber and chemical fiber, and a high-pressure waterjetting treatment is applied to the first fiber layer. The pulp fibercontent of the first fiber layer is 30% by mass to 70% by mass. Thechemical fiber content of the first fiber layer is 70% by mass to 30% bymass, and the average fiber length of the chemical fiber is 20 mm orless. The second fiber layer is arranged by laminating the second fiberlayer to the first fiber layer, and the pulp fiber content of the secondfiber layer is 70% by mass to 100% by mass.

Detailed descriptions will be provided hereinbelow for the embodimentsof the present invention. The present invention is not limited to theembodiments at all. The present invention can be carried out by applyingmodifications to the present invention within the scope of the object ofthe present invention. Duplicated descriptions will be omitted wheneverdeemed necessary. This omission should not be construed as limiting thepresent invention.

Wrapping Sheet First Embodiment

FIG. 1 is a schematic view showing a first embodiment of a wrappingsheet according to the present invention. A two-layered laminatewrapping sheet 70 has a structure in which a first fiber layer 21 and asecond fiber layer 22 are laminated to each other. The first fiber layer21 includes pulp fiber 24 and chemical fiber 25 which are entangled witheach other by high-pressure water jetting, which will be described indetail later. The entanglement of the pulp fiber 24 and the chemicalfiber 25 by high-pressure water jetting rearranges the pulp fiber 24 andthe chemical, fiber 25 so that the overall fiber density of the firstfiber layer 21 is uneven. This provides the first fiber layer 21 betterappearances, and enhances the flexibility of the first fiber layer 21.

The inclusion of the pulp fiber 24 in the first fiber layer 21 increasesthe strength of the first layer 21.

Various publicly-known pulp fibers can be used as the pulp fiber 24 forthe first fiber layer 21. Examples of the publicly-known pulp fibersinclude LBKP, NBKP, wood pulp, hemp, non-wood pulp such as cotton,regenerated cellulose, acetate fiber, PVA (Polyvinyl Alcohol) fiber, CMC(Carboxyl Methyl Cellulose) fiber. These fibers may be used singly or incombination.

The inclusion of the chemical fiber 25 in the first fiber layer 21 bulksup the first fiber layer 21, and thus imparts flexibility to the firstfiber layer 21. This makes it possible to offer the first fiber layers21 having a soft tactile impression. It is desirable to use the chemicalfiber 25 whose fineness is smaller than that of the pulp fiber 24. Theuse of such a chemical fiber 25 enhances the hydrolytic property and theair tightness property of the first fiber layer 21.

The chemical fiber 25 used in the first fiber layer 21 may be of asynthetic type or of a regenerated type. Various publicly-known chemicalfibers can be used as the chemical fiber 25. Examples of thepublicly-known chemical fibers include: fibrillated rayon, regeneratedcellulose, acryl, polyethylene, acetate, polyolefin, polypropylene,polystyrene, polyester fiber, polyethylene telephthalate, polybutylenetelephthalate, polytrimetylene telephthalate and their copolymers;polyamide fiber such as nylon 6 and nylon 6, 6; polyacrylonitrile fiber;acrylic fiber; vinylon fiber; splittable fiber; and synthetic pulp.These chemical fibers may be used singly or in combination.

It is desirable that beaten NBKP, beaten LBKP or the like should be usedfor the purpose of enhancing the air tightness property of the secondfiber layer 22.

It is desirable that the pulp fiber 24 content of the first fiber layer21 as a whole should be 30% by mass to 70% by mass, and that thechemical fiber 25 content of the first fiber layer 21 as a whole shouldbe 70% by mass to 30% by mass. The adoption of such contents causes thefirst fiber layer 21 to have a higher strength, and makes it possiblefor the first fiber layer 21 to be easily dispersed by water.

If the pulp fiber 24 content thereof is less than 30% by mass, thesmaller pulp fiber content thereof makes the chemical fiber 25 contentthereof too large. As a result, the first fiber layer 21 is hard to bedispersed by water. By contrast, if the pulp fiber 24 content thereof ismore than 70% by mass, the larger pulp fiber 24 content thereof makesthe chemical fiber 25 content thereof too small. As a result, the firstfiber layer 21 is hard to be dispersed by water.

If the chemical fiber 25 content of the first fiber layer 21 is lessthan 30% by mass, the smaller chemical fiber content thereof makes itimpossible to obtain a predetermined entanglement strength for the firstfiber layer 21 when the chemical fiber 25 and the pulp fiber 24 areentangled by high-pressure water jetting. This makes it difficult tosecure the flexibility for the first fiber layer 21. On the other hand,if the chemical fiber 25 content thereof is more than 70% by mass, thelarger chemical fiber content thereof makes the entanglement strengthtoo high. This makes the first fiber layer 21 hard to be dispersed bywater.

It is desirable that the average fiber length of the chemical fiber 25in the first fiber layer 21 should be 20 mm or less. By setting theaverage fiber length of the chemical fiber 25 at 20 mm or less, it ispossible to easily disperse the fibers by water flow when thetwo-layered laminate wrapping sheet 70 is discarded into water. Thissetting also prevents the formation from being degraded while the layeris manufactured. This setting further prevents the hydrolytic propertyof the first fiber layer 21 from degrading in aseptic tank of, forexample, a toilet. After the first fiber layer 21 is hydrolyzed in theseptic tank, the setting prevents the first fiber layer 21 from gettingentangled with the diffuser tube, and thus to prevent the first fiberlayer 21 from hindering the aeration, as well as damaging the diffusertube.

The basis weight of the first fiber layer 21 can be changed depending onthe intended use of the two-layered laminate wrapping sheet 70 wheneverdeemed necessary. It is desirable, however, that the basis weight of thefirst fiber layer 21 should be 10 g/m² to 30 g/m². The setting of thebasis weight of the first fiber layer 21 in this range keeps the firstfiber layer 21 strong to a certain degree. If the basis weight of thefirst fiber layer 21 is less than 10 g/m², the texture of the firstfiber layer 21 may be disturbed while treated by high-pressure waterjetting in some cases, and concurrently the first fiber layer 21 may notexert its entanglement effect. On the other hand, if the basis weight ofthe first fiber layer 21 is more than 30 g/m², the higher basis weightdegrades the hydrolytic property of the first fiber layer 21, andincreases the material costs.

Unlike the first fiber layer 21, the second fiber layer 22 can beobtained through a regular forming method without entangling the pulpfiber 24 and the chemical fiber 25 by high-pressure water jetting. Thesecond fiber layer 22 and the first fiber layer 21 are integrallylaminated to each other. Because the second fiber layer 22 is madewithout entangling the pulp fiber 24 and the in the chemical fiber 25 byhigh-pressure water jetting, the hermetic property of the second fiberlayer 22 is enhanced. Thus, the second fiber layer 22 is thus capable ofeffectively preventing foreign matters from getting in beyond the secondfiber layer 22 from outside.

The inclusion of the pulp fibers 24 in the second fiber layer 22 canenhance the strength of the second fiber layer 22.

Various publicly-known pulp fibers can be used as the pulp fibers 24 forthe second fiber layer 22. Examples of the publicly-known pulp fibersinclude LBKP, NBKP, wood pulp, hemp, non-wood pulp such as cotton,regenerated cellulose, acetate fiber, PVA fiber, and CMC fiber. Thesefibers may be used singly or in combination. In addition, pulp fiber 24which is the same as that used for the first fiber layer 21 may be usedfor the second fiber layer 22. Otherwise, pulp fiber 24 different fromthat used for the first fiber layer 21 may be used for the second fiberlayer 22.

It is more desirable that beaten NBKP, beaten LBKP or the like should beused for the purpose of enhancing the hermetic property of the secondfiber layer 22.

The inclusion of the chemical fiber 25 in the second fiber layer 22bulks the second fiber layer 22, and thus imparts flexibility to thesecond fiber layer 22. This makes it possible to offer the second fiberlayer 22 having a soft tactile impression. Furthermore, it is desirablethat the chemical fiber 25 whose fineness is smaller than that of thepulp fiber 24 should be used. The use of such a chemical fiber 25 canenhance the hydrolytic property and the hermetic property of the secondfiber layer 22.

The chemical fiber 25 used in the second fiber layer 22 may be of asynthetic type or of a regenerated type. Various publicly-known chemicalfibers can be used as the chemical fiber for the second fiber layer 22.Examples of the publicly-known chemical fibers include: fibrillatedrayon, regenerated cellulose, acryl, polyethylene, acetate, polyolefin,polypropylene, polystyrene, polyester fiber, polyethylene telephthalate,polybutylene telephthalate, polytrimetylene telephthalate and theircopolymers; polyamide fiber such as nylon 6 and nylon 6,6;polyacrylonitrile fiber; acrylic fiber; vinylon fiber; splittable fiber;and synthetic pulp. These chemical fibers may be used singly or incombination. In addition, the chemical fiber 25 which are the same asthat used for the first fiber layer 21 may be used for the second fiberlayer 22. Otherwise, the pulp fiber 25 different from that used for thefirst fiber layer 21 may be used for the second fiber layer 22.

It is desirable that the pulp fiber 24 content of the second fiber layer22 as a whole should be 70% by mass to 100% by mass, and that thechemical fiber 25 content of the second fiber layer 22 as a whole shouldbe 30% by mass or less. The adoption of such contents increases theair-flow resistance value and enhances the hermetic property of thesecond fiber layer 22. This makes it possible for the second fiber layer22 to effectively prevent foreign matters from getting in beyond thesecond fiber layer 22 from outside.

If the pulp fiber 24 content thereof is less than 70% by mass, thesmaller pulp fiber content thereof makes the chemical fiber 25 contentthereof too large. As a result, the second fiber layer 22 is hard tohydrolyze. By contrast, if the chemical fiber 25 content thereof is morethan 30% by mass, the larger chemical fiber content thereof causestroubles on the production process while the second fiber layer 22 ismanufactured. Examples of the troubles include: increasing thedenseness; degrading the water-filtering property; and reducing thefiber yields. In addition, the larger chemical fiber content thereofhardens the second fiber layer 22 too much. As a result, for example,the second fiber layer 22 becomes apt to get creased while used as anindividual-wrapping material. Furthermore, the larger chemical pulpcontent thereof may increase the material costs in some cases.

It is desirable that the average fiber length of the chemical fiber 25in the second fiber layer 22 should be 20 mm or less. The setting of theaverage fiber length of the chemical fiber 25 at 20 mm or less makes itpossible to disperse the fibers by water easily when the two-layeredlaminate wrapping sheet 70 is discarded into water. This setting alsoprevents the formation from being degraded while the second fiber layer22 is manufactured. This setting further prevents the hydrolyticproperty of the second fiber layer 22 from degrading in a septic tankof, for example, a toilet. After the second fiber layer 22 is hydrolyzedin the septic tank, too, the setting prevents the fibers from gettingentangled with the diffuser tube, and thus to prevent the fibers fromhindering the aeration, as well as preventing the fibers from damagingthe diffuser tube.

The basis weight of the second fiber layer 22 can be changed dependingon the intended use of the two-layered laminate wrapping sheet 70whenever deemed necessary. It is desirable, however, that the basisweight of the second fiber layer 22 should be 15 g/m² to 30 g/m². Thesetting of the basis weight of the second fiber layer 22 in this rangekeeps the second fiber layer 22 strong to a certain degree. If the basisweight of the second fiber layer 22 is less than 15 g/m², the smallerbasis weight may degrade the hermetic property of the second fiber layer22 in some cases. On the other hand, if the basis weight of the secondfiber layer 22 is more than 30 g/m², the larger basis weight hardens thesecond fiber layer 22, causes the sheet to make sounds, makes the sheetcrease easily, and deteriorates the tactile impression.

The basis weight of the two-layered laminate wrapping sheet 70 can bechanged depending on the intended use of the two-layered laminatewrapping sheet 70 whenever deemed necessary. It is desirable, however,that the basis weight of the two-layered laminate wrapping sheet 70should be 25 g/m² to 60 g/m². If the basis weight of the two-layeredlaminate wrapping sheet 70 is less than 25 g/m², the smaller basisweight may degrade the hermetic property of the two-layered laminatewrapping sheet 70 in some cases. On the other hand, if the basis weightof the two-layered laminate wrapping sheet 70 is more than 60 g/m², thelarger basis weight degrades the hydrolytic property of the two-layeredlaminate wrapping sheet 70.

It is desirable that the dry strength of the two-layered laminatewrapping sheet 70 should be 2.0 N/25 mm or more in the machine directionMD. It is more desirable that the dry strength thereof should be 5.0N/25 mm in the machine direction MD. In addition, it is desirable thatthe dry strength of the two-layered laminate wrapping sheet 70 should be2.0 N/25 mm or more in the cross direction CD. It is more desirable thatthe dry strength thereof should be 2.5 N/25 mm or more in the crossdirection CD. The setting of the dry strengths thereof in such rangesmakes it possible for the two-layered laminate wrapping sheet 70 tomaintain its required strengths. Moreover, it is desirable that the wetstrength of the two-layered laminate wrapping sheet 70 should be 2.0N/25 mm or more both in the machine direction MD and in the crossdirection CD. The setting of the wet strengths thereof in such rangesmakes it possible for the two-layered laminate wrapping sheet 70 tomaintain its required strengths even while in a wet condition.

Once the two-layered laminate wrapping sheet 70 is discarded into atoilet bowl or the like, the pulp fiber 24 included in the first fiberlayer 21 and the second fiber layer 22 immediately starts to bedissolved by the water flow of a large amount of water in the toiletbowl. In the first fiber layer 21, once the pulp fiber 24 starts to bedissolved, the chemical fiber 25 which is entangled with the pulp fiber24 starts to be dissolved into the water. The untangling of the pulpfibers 24 and the chemical fiber 25 quickly disperses the fibers.

The hydrolytic property of the two-layered laminate wrapping sheet 70can be changed depending on the intended use and size of the two-layeredlaminate wrapping sheet 70 whenever deemed necessary. Take a case where,for example, the two-layered laminate wrapping sheet 70 is a squaredsheet with a size of 10 cm×10 cm. When the two-layered laminate wrappingsheet 70 is shaken at a shaking speed of 240 rpm for 30 minutes with thetwo-layered laminate wrapping sheet 70 being placed in 800 ml ofdistilled water, it is desirable that the two-layered laminate wrappingsheet 70 should be so dispersed into water that even the largestremaining piece of the two-layered laminate wrapping sheet 70 becomes 50cm² or less in size. It is more desirable that the two-layered laminatewrapping sheet 70 should be so dispersed into water that even thelargest remaining piece thereof becomes 25 cm² or less in size. It isfar more desirable that the two-layered laminate wrapping sheet 70should be so dispersed into water that no trace of the original formthereof remains. If the two-layered laminate wrapping sheet 70 is sodispersed into water that the largest remaining piece thereof is stillnot less than 50 cm² in size, in some cases, the largest remaining piecethereof may clog the toilet drain or the like when the two-layeredlaminate wrapping sheet 70 is discarded by toilet flushing or the like.

A pattern may be formed in the first fiber layer 21 and the second fiberlayer 22 by changing the basis weight of each of the first fiber layer21 and the second fiber layer 22, depending on the necessity, to such anextent that the hydrolytic properties thereof are maintained.

At least one part of the first fiber layer 21 and/or the second fiberlayer 22 may be designed to have a predetermined water resistingproperty by including a sizing agent therein. A rosin derivative, AKD(Alkyl Ketene Diner) and ASA (Alkenyl Succinic Anhydride) can be citedas examples of the sizing agent.

The first fiber layer 21 and/or the second fiber layer 22 may be coloredto such an extent that the hydrolytic property thereof is maintaineddepending on the necessity. Various publicly-known adhesion promoterscan be used as the adhesion promoter for the color development. Examplesof the usable adhesion promoters include: common direct cationic dyessuch as CI. Direct Red 81; and cationic dyes each including a sizingagent. It should be noted that the first fiber layer 21 and the secondfiber layer 22 may be colored in different colors.

In addition, depending on the necessity, the two-layered laminatewrapping sheet 70 can be turned into a heat sealable one by blending athermally-adhesive fiber, which does not develop its thermaladhesiveness at a drying temperature used when the chemical fiber 25 ismanufactured, into the first fiber layer 1 and the second fiber layer 2.In this case, if the average fiber length of the thermally-adhesivefiber is set at 20 mm or less, it is possible to prevent the hydrolyticproperty thereof from being degraded. For this reason, the two-layeredlaminate wrapping sheet 70 into which the thermally-adhesive fiber isblended can exhibit the heat-seal property, the air tightness propertyand the hydrolytic property at the same time, because part of thetwo-layered laminate wrapping sheet 70 which is not heat-sealed iscapable of maintaining its hydrolytic property fully.

In the case where the two-layered laminate wrapping sheet 70 isdiscarded into a large amount of water in a flush toilet, and the like,first of all, the second fiber layer 22 is hydrolyzed, and thehydrolysis of the first fiber layer 22 is thus accelerated. Thereby, thetwo-layered laminate wrapping sheet 70 is hydrolyzed.

Second Embodiment

A second embodiment of the wrapping sheet according to the presentinvention is the same as the first embodiment thereof except that, asshown in FIG. 2, a third fiber layer 23 is arranged on a side of thesecond fiber layer 22 which does not oppose to the first fiber layer 21,and the first to third fiber layers 21, 22 and 23 are laminated one toanother. Like the first fiber layer 21, the third fiber layer 23includes the pulp fiber 24 and the chemical fiber 25 which are entangledwith each other. These two fibers are obtained by entangling them witheach other by high-pressure water jetting treatment. The entanglement byhigh-pressure water jetting treatment rearranges the pulp fiber 24 andthe chemical fiber 25 so that the overall fiber density of the thirdfiber layer 23 is uneven. This provides the third fiber layer 23 betterappearances, and enhances the flexibility of the third fiber layer 23.

The inclusion of the pulp fiber 24 in the third fiber layer 23 increasesthe strength of the third layer 23.

Various publicly-known pulp fibers can be used as the pulp fiber 24 forthe third fiber layer 23. Examples of the publicly-known pulp fibersinclude LBKP, NBKP, wood pulp, hemp, non-wood pulp such as cotton,regenerated cellulose, acetate fiber, PVA (Polyvinyl Alcohol) fiber, CMC(Carboxyl Methyl Cellulose) fiber. These fibers may be used singly or incombination. The pulp fiber 24 used for the third fiber layer 23 may bethe same as the pulp fiber 24 used for the first layer 21. Otherwise,the pulp fiber 24 used for the third fiber layer 23 may be differentfrom the pulp fiber 24 used for the first fiber layer 21.

The inclusion of the chemical fiber 25 in the third fiber layer 23 bulksup the third fiber layer 23, and thus imparts flexibility to the thirdfiber layer 23. This makes it possible to offer the third fiber layers23 having a soft tactile impression. It is desirable to use the chemicalfiber 25 whose fineness is smaller than that of the pulp fiber 24. Theuse of such a chemical fiber 25 enhances the hydrolytic property and theair tightness property of the third fiber layer 23.

The chemical fiber 25 used in the third fiber layer 23 may be of asynthetic type or of a regenerated type. Various publicly-known chemicalfibers can be used as the chemical fiber 25 for the first fiber layer21. Examples of the publicly-known chemical fibers include: fibrillatedrayon, regenerated cellulose, acryl, polyethylene, acetate, polyolefin,polypropylene, polystyrene, polyester fiber, polyethylene telephthalate,polybutylene telephthalate, polytrimetylene telephthalate and theircopolymers; polyamide fiber such as nylon 6 and nylon 6, 6;polyacrylonitrile fiber; acrylic fiber; vinylon fiber; splittable fiber;and synthetic pulp. These chemical fibers may be used singly or incombination. The chemical fiber 25 used for the third fiber layer 23 maybe the same as the chemical fiber 25 used for the first layer 21.Otherwise, the chemical fiber 25 used for the third fiber layer 23 maybe different from the chemical fiber 25 used for the first fiber layer21.

It is desirable that beaten NBKP, beaten LBKP or the like should be usedfor the purpose of enhancing the air tightness property of the secondfiber layer 22.

It is desirable that the pulp fiber 24 content of the third fiber layer23 as a whole should be 30% by mass to 70% by mass, and that thechemical fiber 25 content of the third fiber layer 23 as a whole shouldbe 70% by mass to 30% by mass. The adoption of such contents causes thethird fiber layer 23 to have a higher strength, and makes it possiblefor the third fiber layer 23 to be easily dispersed by water. The pulpfiber 24 content and the chemical fiber 25 content of the third fiberlayer 23 may be the same as the pulp fiber 24 content and the chemicalfiber 25 content of the first fiber layer 21, respectively. Otherwise,pulp fiber 24 content and the chemical fiber 25 content of the thirdfiber layer 23 may be different from the pulp fiber 24 content and thechemical fiber 25 content of the first fiber layer 21.

If the pulp fiber 24 content thereof is less than 30% by mass, thesmaller pulp fiber content thereof makes the chemical fiber 25 contentthereof too large. As a result, the third fiber layer 23 is hard tohydrolyze. By contrast, if the pulp fiber 24 content thereof is morethan 70% by mass, the larger pulp fiber 24 content thereof makes thechemical fiber 25 content thereof too small. As a result, the thirdfiber layer 23 is hard to be dispersed by water.

If the chemical fiber 25 content of the third fiber layer 23 is lessthan 30% by mass, the smaller chemical fiber content thereof makes itimpossible to secure a predetermined entanglement strength for the thirdfiber layer 23 when the chemical fiber 25 and the pulp fiber 24 areentangled by high-pressure water jetting treatment. This makes itdifficult to secure the flexibility for the third fiber layer 23. On theother hand, if the chemical fiber 25 content thereof is more than 70% bymass, the larger chemical fiber content thereof makes the entanglementstrength too high. This makes the first fiber layer 21 hard to hydrolyzeeasily.

It is desirable that the average fiber length of the chemical fiber 25in the third fiber layer 23 should be 20 mm or less. By setting theaverage fiber length of the chemical fiber 25 at 20 mm or less, it ispossible to easily disperse the fibers by water flow when thethree-layered laminate wrapping sheet 80 is discarded into water. Thissetting also prevents the formation from being degraded while the thirdfiber layer 23 is manufactured. This setting further prevents thehydrolytic property of the third fiber layer 23 from degrading in aseptic tank of, for example, toilet. After the third fiber layer 23 ishydrolyzed in the septic tank, the setting prevents the fibers fromgetting entangled with the diffuser tube, and thus to prevent the fibersfrom hindering the aeration, as well as preventing the fibers fromdamaging the diffuser tube.

The basis weight of the third fiber layer 23 can be changed depending onthe intended use of the three-layered laminate wrapping sheet 80whenever deemed necessary. It is desirable, however, that the basisweight of the third fiber layer 23 should be 10 g/m² to 30 g/m². Thesetting of the basis weight of the third fiber layer 23 in this rangekeeps the third fiber layer 23 strong to a certain degree. If the basisweight of the third fiber layer 23 is less than 10 g/m², the texture ofthe third fiber layer 23 may be disturbed while treated by high-pressurewater jetting in some cases, and concurrently the third fiber layer 23may not exert its entanglement effect. On the other hand, if the basisweight of the third fiber layer 23 is more 30 g/m², the higher basisweight degrades the hydrolytic property of the third fiber layer 23, andincreases the material costs. The basis weight of the third fiber layer23 may be the same as that of the first fiber layer 21, or may bedifferent from that of the first fiber layer 21.

In addition, the basis weight of the three-layered laminate wrappingsheet 80 can be changed depending on the intended use of thethree-layered laminate wrapping sheet 80 whenever deemed necessary. Itis desirable that the basis weight thereof should be 35 g/cm² to 60g/cm². If the basis weight thereof is less than 35 g/m², the smallerbasis weight thereof may degrade the air tightness property of thethree-layered laminate wrapping sheet 80 in some cases. By contrast, ifthe basis weight thereof is more than 60 g/cm², the larger basis weightthereof degrades the hydrolytic property of the three-layered laminatewrapping sheet 80.

It is desirable that the dry strength of the three-layered laminatewrapping sheet 80 should be 2.0 N/25 mm or more in the machine directionMD. It is more desirable that the dry strength thereof should be 5.0N/25 mm in the machine direction MD. In addition, it is desirable thatthe dry strength of the three-layered laminate wrapping sheet 80 shouldbe 2.0 N/25 mm or more in the cross direction CD. It is more desirablethat the dry strength thereof should be 2.5 N/25 mm or more in the crossdirection CD. The setting of the dry strengths thereof in such rangesmakes it possible for the three-layered laminate wrapping sheet 80 tomaintain its required strengths. Moreover, it is desirable that the wetstrength of the three-layered laminate wrapping sheet 80 should be 2.0N/25 mm or more both in the machine direction MD and in the crossdirection CD. The setting of the wet strengths thereof in such rangesmakes it possible for the three-layered laminate wrapping sheet 80 tomaintain its required strengths even while in a wet condition.

Once the three-layered laminate wrapping sheet 80 is discarded into atoilet bowl or the like, the pulp fiber 24 included in the first fiberlayer 21 to the third fiber layers 23 immediately starts to be dissolvedby the water flow of a large amount of water in the toilet bowl. Oncethe pulp fiber 24 in the first fiber layer 21 and the third fiber layer23 starts to be dissolved, the chemical fiber 25 which is entangled withthe pulp fiber 24 starts to be dissolved into the water. The untanglingof the pulp fibers 24 and the chemical fiber 25 quickly disperses thefibers.

The hydrolytic property of the three-layered laminate wrapping sheet 80can be changed depending on the intended use and size of thethree-layered laminate wrapping sheet 80 whenever deemed necessary. Takea case where, for example, the three-layered laminate wrapping sheet 80is a squared sheet with a size of 10 cm×10 cm. When the three-layeredlaminate wrapping sheet 80 is shaken at a shaking speed of 240 rpm for30 minutes with the sheet being placed in 800 ml of distilled water, itis desirable that the three-layered laminate wrapping sheet 80 should beso dispersed into water that even the largest remaining piece of thethree-layered laminate wrapping sheet 80 becomes 50 cm² or less in size.It is more desirable that the three-layered laminate wrapping sheet 80should be so dispersed into water that even the largest remaining piecethereof becomes 25 cm² or less in size. It is far more desirable thatthe three-layered laminate wrapping sheet 80 should be so dispersed intowater that no trace of the original form thereof remains. If thethree-layered laminate wrapping sheet 80 is so dispersed into water thatthe largest remaining piece thereof is still not less than 50 cm² insize, in some cases, the largest remaining piece thereof may clog thetoilet drain or the like when the three-layered laminate wrapping sheet80 is discarded by toilet flushing or the like.

The three-layered laminate wrapping sheet 80 can be turned into a heatsealable one by blending a thermally-adhesive fiber, which does notdevelop its thermal adhesiveness at a drying temperature used when thechemical fiber 25 is manufactured, into the first fiber layer 21 and thethird fiber layer 23 depending on the necessity. In this case, if theaverage fiber length of the thermally-adhesive fiber is set at 20 mm orless, it is possible to prevent the hydrolytic property thereof frombeing degraded. For this reason, the three-layered laminate wrappingsheet 80 into which the thermally-adhesive fiber is blended can exhibitthe heat-seal property, the air tightness property and the hydrolyticproperty at the same time, because part of the three-layered laminatewrapping sheet 80 which is not heat-sealed is capable of maintaining itshydrolytic property fully.

In a case where the three-layered laminate wrapping sheet 80 isdiscarded into a large amount of water in a flush toilet, and the like,first of all, the second fiber layer 22 is hydrolyzed, and the firstfiber layer 21 to the third fiber layer 23 are thus separated from eachother. The layer separation accelerates the hydrolysis of the firstfiber layer 21 and third fiber layer 23. Finally, the three-layeredlaminate wrapping sheet 80 is hydrolyzed.

[Individual Package]

FIGS. 3 and 4 are schematic view showing an outline of an individualpackage 1 according to the first embodiment. As shown in FIGS. 3 and 4,the individual package 1 includes an interlabial pad 10 and a wrappingmaterial 20 wrapping the interlabial pad 10. For explanatoryconvenience, the absorbent article is explained as being the interlabialpad 10. However, the absorbent article is not limited to the interlabialpad 10, and includes a sanitary napkin and a pantiliner.

FIG. 5 shows a perspective view of the interlabial pad 10 as theabsorbent article. The interlabial pad 10 is folded into halves alongthe center axis which extends in the longitudinal direction. Theinterlabial pad 10 is worn with at least a part of the pad beinginterposed between the minor labia in the labia in a way that at leastone part of the pad near the center axis contacts the vestibular floorin the labia.

The interlabial pad 10 is worn with a part of the pad being interposedbetween the labia of the wearer. As shown in FIG. 5, the interlabial pad10 includes: a fluid-permeable top sheet 12, which is a coveringmaterial, and which exhibits a fluid permeability property; afluid-impermeable back sheet 13, which is a covering material, and whichexhibits a fluid-impermeability property which virtually does not allowany fluid to permeate the back sheet; and an absorbent 15, which isarranged between the fluid-permeable top sheet 12 and thefluid-impermeable back sheet 13, and which exhibits a fluid retentionproperty. In addition, the interlabial pad 10 includes a peripheral part11 constituting the border of the interlabial pad 10. The peripheralpart 11 includes a front end part 10 a and a rear end part 10 b whichare located in the two ends of the interlabial pad 10 in thelongitudinal direction thereof. Furthermore, the interlabial pad 10 isfolded into halves along the center line k in the longitudinal directionthereof with the folded halves of the fluid-impermeable back sheet 13being lied over one another when the interlabial pad 10 is worn.Moreover, the interlabial pad 10 includes a vestibular floor touchingarea 14 which contacts the vestibular floor of a wearer when theinterlabial pad 10 is worn.

The fluid-permeable top sheet 12 and the fluid-impermeable back sheet 13both for covering an absorbent member 15 includes: a fluid-permeable topsheet front end part 12 a and a fluid-impermeable back sheet front endpart 13 a both facing the pubis while the interlabial pad 10 is worn;and a fluid-impermeable top sheet rear end part 12 b and afluid-impermeable back sheet rear end part 13 b both situated to thebuttocks while the pad 10 is worn. In the case of the presentembodiment, the fluid-permeable top sheet front end part 12 a and thefluid-impermeable back sheet front part 13 a constitute the front endpart 10 a of the peripheral part 11 of the interlabial pad 10, andfluid-permeable the top sheet rear end part 12 b and thefluid-impermeable back sheet rear end part 13 b constitute the rear endpart 10 b of the peripheral part 11 thereof.

The interlabial pad 10 is formed in a shape such as oval, gourd-shaped,teardrop-shaped and the like, so that the interlabial pad 10 fit to thefemale labia. With regard to the external dimensions of the interlabialpad 10, it is desirable that the width of the interlabial pad 10 in thecenter axial direction thereof should be 40 mm to 180 mm. It is moredesirable that the width thereof in the center axial direction should be80 mm to 120 mm. In addition, it is desirable that the width of theinterlabial pad 10 in a direction perpendicular to the center axisshould be 20 mm to 100 mm. It is more desirable that the width thereofin the perpendicular direction should be 50 mm to 80 mm. It should benoted that the width thereof in the direction perpendicular to thecenter axis is the width of the interlabial pad 10 which is flat beforefolded into halves. When the interlabial pad 10 is worn while folded inhalves, the dimension of the interlabial pad 10 in the perpendiculardirection should be almost a half of the desirable width. As describedabove, the interlabial pad 10 is basically of a type which is interposedbetween the labia with the flat pad being folded into halves. Instead,however, a bar-like shape and a cylinder-like shape may be adopted forthe interlabial pad 10. The width of the pad other than the type whichis worn with the flat pad being folded in halves, the width of the padin the direction perpendicular to the center axis should be almost ahalf of the above-described desirable width.

A survey conducted by the applicants concludes: an average length of thecunnus (from the anterior labial commissure to the posterior labialcommissure) is approximately 80 mm; the average distance from theclitoris to the ostium vaginae is approximately 40 mm; the distance fromthe ostium vaginae to the anus is approximately 45 mm. For the purposeof preventing the menstrual blood from flowing out, it is desirable thatthe front edge end portion of the interlabial pad 10 should cover up toat least the clitoris. For the purpose of preventing the pad from comingout of place due to movement of the muscles of the buttocks, it isdesirable that the rear edge end portion of the interlabial pad 10should not reach the anus. For the purpose of satisfying theseconditions, it is desirable that the external dimensions of theinterlabial pad 10 should be within the foregoing ranges.

It is desirable that the absorbent article according to the presentinvention should be made of a water-dispersible material, abiodegradable material and a water-soluble material. This is because thebelow-described wrapping material 20 is water-degradable. After used,the absorbent article thus made can be discarded into the toilet. Thus,making it possible to discard the absorbent article conveniently andcleanly, and reduce the amount of garbage in the toilet.

“Water-dispersible” is synonymous to water-degradable.“Water-dispersible” is used to describe a property which does not allowa limited small amount of moisture or menstrual blood to affect aproduct while the product is in use, but which causes ingredient fibersof the product to be dispersed in a large amount of water or water flowwithin a range that the dispersed fibers do not clog at least a drainagepipe of a regular toilet.

“Biodegradable” is used to describe a property which causes ingredientsubstances constituting a product to be degraded into gases such ascarbon dioxide and methane, water, and biomass through a naturalecological process in the environment in which bacteria includingactinomycetes, and other microorganisms exist. In addition,biodegradability (or biodegradation speed, and degree of biodegradation)of the product is correspondingly treated as that of a natural materialsuch as fallen leaves, and as a synthetic polymer recognized as beingbiodegradable.

“Water-soluble” is used to describe a property which does not allow alimited small amount of moisture or menstrual blood to affect a productwhile the product is in use, but which causes the product to bedissolved in a large amount of water or water flow.

As shown in FIGS. 3 and 4, the wrapping material 20 contains the wholeinterlabial pad 10 with the pad being wrapped with the wrapping material20. The wrapping material includes an unsealed opening 26. A part of thewrapping material 20 overlaps another part of the wrapping material 20in the vicinity of unsealed opening 26. The overlapping parts of thewrapping material 20 are adhered to each other to be able to unseal anddetach.

The wrapping material 20 shown in FIG. 3 is provided with a protectivearea Y1 which has a higher rigidity than that of the peripheral part 11of the interlabial pad 10. The width dimension of the protective area Y1is large enough to cover the vestibular floor touching area 14, in otherwords covers 5% to 70% of the width of the interlabial pad 10 while inthe state of being wrapped with the wrapping material 20. The protectivearea Y1 is unintermittently provided to the wrapping material 20 in thelongitudinal direction. An embossing seal 28, for connecting a part ofthe wrapping material 20 to another part of the wrapping material 20 isprovided to an end side of the wrapping material in the longitudinaldirection of the wrapping material 20. The rigidity of the protectivearea Y1 can be increased by this embossing seal 28, as well. An adhesiveis provided in the longitudinal direction between the overlapping partsof the wrapping material 20 for the purpose of increasing theair-tightness of the wrapping material 20. This adhesive increases therigidity of the wrapping material 20. For this reason, it is possiblefor the vestibular floor touching area 14 to keep its original shapeeven if an external pressure is applied to the individual package 1while the individual package 1 is being carried. In addition, theindividual package 1 is a package of the interlabial pad 10 hermeticallysealed with the wrapping material 20 with the air being filled inside.For this reason, even if the individual package 1 is dropped, not onlythe peripheral part 11 but also the other parts of the interlabial pad10 inside the individual package 1 are prevented from being damaged.

The embossing seal 28, for connecting a part of the wrapping material 20to another part of the wrapping material 20 constituting the wrappingmaterial 20, may be provided to the entire peripheral portion of thewrapping material 20 additionally. Furthermore, an unsealing part 27configured by the overlapping parts of the wrapping material 20 may beprovided with an adhesive tying tape 29 for the purpose of increasingthe unsealability of the unsealing part 27.

The front end part 10 a of the peripheral part 11 of the interlabial pad10 tends to come into contact with the clitoris of a wearer while theinterlabial pad 10 is worn. The rear end part 10 b thereof tends to comeinto contact with the anus of the wearer while the interlabial pad 10 isworn. For this reason, additional protective areas Y1 are provided tothe wrapping material 20 depending on the necessity. This prevents thefront end part 10 a and the rear end part 10 b from warping. As aresult, it is possible to prevent the font end part 10 a and the rearend part 10 b from hurting the clitoris and anus of the wearer,respectively.

The protective area Y1 may be provided in order to protect the entireperipheral part 11 of the interlabial pad 10. Otherwise, the protectivearea Y1 may be provided in order to protect the vestibular floortouching area 14 only. Otherwise, the protective area Y1 may be providedin order to protect the front end part 10 a (including thefluid-permeable top sheet front end part 12 a and the fluid-impermeableback sheet front end part 13 a) and the rear end part 10 b (includingthe fluid-permeable top sheet rear end part 12 b and thefluid-impermeable back sheet rear end part 13 b) only.

It is desirable that the buckling strength of the protective area Y1should be 100 mN or more, but 2000 mN or less. The buckling strengthwithin this range prevents the peripheral part 11 from warping during awrapping process, or while the individual package 1 is being carried. Inaddition, it is desirable that the buckling strength of the peripheralpart 11 of the interlabial pad 10 should be 50 mN or more, but 400 mN orless.

The wrapping material 20 is the two-layered laminate wrapping sheet 70,which has a configuration in which the first fiber layer 21 is arrangedin the outer side of the individual package 1 as shown by thecross-section taken along the X-X′ line of FIG. 4. The use of thetwo-layered laminate wrapping sheet 70 as the wrapping material 20provides the wrapping material 20 better appearance and more flexible.In stead of the two-layered laminate wrapping sheet 70, as shown in FIG.6, the three layered laminate wrapping sheet 80 may be used as thewrapping material 20.

[Method of Manufacturing a Wrapping Sheet]

A method of manufacturing a wrapping sheet according to the presentinvention is characterized by including: a step of forming a first fiberlayer 21 by forming pulp fiber 24 and chemical fiber 25 into a fiber webby a wet forming method, and subsequently by applying a high-pressurewater jetting treatment to the two sides or one side of the fiber web,to entangle the pulp fiber 24 and the chemical fiber 25; a step offorming pulp fiber 24 and chemical fiber 25 into a second fiber layer22; and a step of conveying the first fiber layer 21, and integrallylaminating the second fiber layer 22 to the first fiber layer 21.

(Method of Manufacturing a Two-Layered Laminated Wrapping Sheet 70)

First of all, a material liquid dispersed in water with a predeterminedconcentration is sent to a first web former 30 and a second web former40, and the material liquid thus sent is made into a first web 31 and asecond web 41. It should be noted that, in a case where the first fiberlayer 21 and the second fiber layer 22 are intended to be colored, asizing agent, a cationic sizing agent, a cationic dye or the like may beadded to the material liquid.

The first fiber layer 21 is formed by forming the pulp fiber 24 and thechemical fiber 25 into the fiber web (the first web 31) by the wetforming method, and thereafter by applying the high-pressure waterjetting treatment to the first web 31. In this respect, the fiber webmeans a sheet-shaped fiber mass in which most ingredient fibers areoriented in the same direction. The fiber web may be made by a dryforming method instead of the wet forming method. For this high-pressurewater jetting treatment, a high-pressure water jetting machine of agenerally-used type is employed.

When the high-pressure water jetting treatment is applied to either orboth sides of the fiber web (the first web 31) by use of a water jetwith a relative high pressure, the pulp fiber 24 and the chemical fiber25 are strongly entangled to each other in parts of the first web wherethe water jet is applied, whereas the two fibers are kept bulked up inthe other parts of the first web where the water jet is not applied.Consequently, in the first fiber layer 21 the pulp fiber 24 and thechemical fiber 25 are highly integrally entangled to each other, and arebulked up, as well as. This exhibits a better air permeability, waterabsorbing property, heat retaining property, softness and the like.

The high-pressure water jetting treatment involves applying a jet ofhigh-pressure water to the pulp fiber 24 and the chemical fiber 25, andthereby entangling parts of the two fibers 24 and 25, and thus combiningthe jet-applied parts thereof together. An apparatus and conditionsemploying a regular technology for manufacturing a non-woven fabric canbe used as an apparatus and conditions for the high-pressure waterjetting treatment.

Detailed descriptions will be herein provided for the high-pressurewater jetting treatment. A fiber web is placed on a conveyer beltcontinuously running, and a jet of high-pressure water is applied to thefiber web placed thereon in a way that the jet passes the fiber web fromits front surface through its back surface. In the case of thishigh-pressure water jetting treatment, properties of the obtainablefirst fiber layer 21 can be changed by changing the weighing capacity ofthe fiber web, the pore size of the jet nozzle, the number of pores inthe jet nozzle, the work load (or energy) supplied for treating thefiber web and the like whenever deemed necessary.

In the case of the present embodiment, it is desirable that thehigh-pressure water jetting treatment should be applied to the fiber web(or the first web 31) in a way that the work load calculated by use ofEquation (1) is 0.05 kW/m² to 0.5 kW/m² for each treatment of onesurface of the fiber web (or the first web 31). If the work load is lessthan 0.05 kW/m², the smaller work load decreases the bulk of the firstfiber layer 21. By contrast, if the work load is more than 0.5 kW/m²,the larger work load may entangle the fibers with each other too much sothat the hydrolytic property of the first fiber layer is degraded, ormay destroy the fiber web. This high-pressure water jetting treatmentcan be applied to either or both sides of the fiber web. If, forexample, the high-pressure water jetting treatment with a work load of0.05 kW/m² to 0.5 kW/m² is applied to either or both sides of the fiberweb once to 6 times, the first fiber layer 21 can be obtained with itsdesirable hydrolytic property and wet strength.

$\begin{matrix}{{{Equation}\mspace{14mu} (1)}\mspace{520mu}} & \; \\{{{Work}\mspace{14mu} {load}\mspace{14mu} \left( {{kW}\text{/}m^{2}} \right)} = {{\begin{bmatrix}{1.63 \times {jet}\mspace{14mu} {pressure}\mspace{14mu} \left( {{kgf}\text{/}{cm}^{2}} \right) \times} \\{{jet}\mspace{14mu} {amount}\mspace{14mu} \left( {m^{3}\text{/}\min} \right)}\end{bmatrix} \div {treatment}}\mspace{14mu} {rate}\mspace{14mu} \left( {m\text{/}\min} \right)}} & \left\lbrack {{Formula}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In the case where the work load is 0.05 kW/m² to 0.5 kW/m², thehigh-pressure water jetting treatment can be applied thereto with acondition that, for example, the pore size of the nozzle is 90 μm to 100μm, and the pores are arranged in the nozzle at intervals of 0.3 mm to2.0 mm in the cross direction CD. In this case, the fibers areappropriately entangled with each other.

After the fiber web (or the first web 31) is made, the high-pressurewater jetting treatment may be applied to the fiber web without dryingthe fiber web. Otherwise, the high-pressure water jetting treatment maybe applied thereto after drying the fiber web.

The high-pressure water jetting treatment may be applied to the formedfirst web 31 which is conveyed to a high-pressure water jettingtreatment unit 32 while placed on a fiber layer forming wire directly.Otherwise, depends on the necessity, the high-pressure water jettingtreatment may be applied to the first web 31 which is conveyed to ahigh-pressure water jetting treatment unit 32 after transferred from thefiber layer forming wire to a patterning wire.

It is desirable that a web forming machine of an inclined tanmo orfourdrinier type which is capable of easily distributing even longingredient fibers randomly should be used as the first web former 30.

The first high-pressure water jetting unit 32 may have a configurationin which the first high-pressure water jetting unit 32 uses a webforming net (not illustrated) with the first web former 30, and in whicha high-pressure water jetting nozzle apparatus (not illustrated) isarranged above the web forming net. Furthermore, in a case where apatterned sheet is intended to be obtained through the high-pressurewater jetting treatment, it is desirable that the high-pressure waterjetting treatment should be applied to the first web 31 by conveying thefirst web 31 to the first high-pressure water jetting treatment unit 32which is arranged in the back of the first web former 30 as shown inFIG. 7.

The first fiber layer 21 may be made through entangling its ingredientfibers with one another by use of needles, air or the like instead of byuse of the high-pressure water jetting treatment.

Unlike the first fiber layer 21, the second fiber layer 22 is formed byintegrally entangling its ingredient pulp fiber 24 and chemical fiber 25through a joint formation process, instead of through the high-pressurewater jetting treatment.

For the purpose of manufacturing the second web 41, types of second webformer 40 can be changed depending on the intended use of thetwo-layered laminate wrapping sheet 70 whenever deemed necessary. It isdesirable that the second web former 40 used for manufacturing thesecond web 41 may be, for example, of a cylinder net type or a formertype which makes it possible to obtain a formation homogeneous.

A first treated web 33 obtained by causing the first high-pressure waterjetting treatment unit 32 to apply the high-pressure water jettingtreatment to the first web 31 is conveyed to the second web former 40.Thereafter, by a first joint former 42, the first treated web 33 thusconveyed is put on the second web 41 formed by the second web former 40,and a wet two-layered laminate wrapping sheet 43 is formed and sent out.This wet two-layered laminate wrapping sheet 43 is conveyed to a dryer60. After dried, the two-layered laminate wrapping sheet 43 is wound upby a winder 90.

(Method of Manufacturing a Three-Layered Laminated Wrapping Sheet 80)

A method of manufacturing a three-layered laminate wrapping sheet 80 isthe same as the method of manufacturing a two-layered laminate wrappingsheet 70 except that the method of manufacturing a three-layeredlaminate wrapping sheet 80 includes a step of laminating a third fiberlayer 23 onto the second fiber layer 22, the third fiber layer 23 beingformed with the same method as is used to form the first fiber layer 21.

A material liquid dispersed in water with a predetermined concentrationis sent to the first web former 30, the second web former 40 and a thirdweb former 50, and the material liquid thus sent is made into the firstweb 31, the second web 41 and a third web 51.

A first treated web 33 obtained by causing the first high-pressure waterjetting treatment unit 32 to apply a high-pressure water jettingtreatment to the first web 31 is conveyed to the second web former 40.Thereafter, by the first joint former 42, the first treated web 33 thusconveyed is put on the second web 41 formed by the second web former 40.

A third treated web 53 obtained by causing a second high-pressure waterjetting unit 52 to apply a high-pressure water jetting treatment to thethird web 51 is conveyed. The third treated web 53 thus conveyed is puton the second web by a second joint former 54, and a wet three-layeredlaminate wrapping sheet 55 is formed. The wet three-layered laminatewrapping sheet 55 thus formed is conveyed to the drier 60. After dried,the three-layered laminate wrapping sheet 55 is wound up by the winder90.

Embodiment

Descriptions will be provided hereinbelow for the examples of thepresent invention. However, these examples are presented just for thepurpose of describing the preferred embodiments of the presentinvention, and accordingly impose no restriction on the presentinvention at all.

For the purpose of evaluating the hydrolytic property and the like ofthe wrapping sheet according to the present invention, wrapping sheetswere formed, and the properties thereof were checked.

[Forming of Two-Layered Laminate Wrapping Sheet]

(Forming of First Fiber Layer)

A mixture of NBKP (softwood chemical pulp) (with a CSF of 720 cc) andNBKP (with a CSF of 600 cc) were used as the pulp fiber 24 of the firstfiber layer. CSF stands for Canadian Standard Freeness.

Rayon fiber (trade name: Corona, manufactured by Daiwabo Rayon Co.,Ltd.) with a fineness of 1.1 dtex and with an average fiber length of 7mm was used as the chemical fiber 25 of the first fiber layer.

The pulp fiber 24 content of the first fiber layer was 50% by mass (fordetail, the NBKP (with a CFS of 720 cc) content of the first fiber layerwas 30% by mass, and the NBKP (with a CFS of 600 cc) content of thefirst fiber layer was 20% by mass). On the other hand, the chemicalfiber 25 content of the first fiber layer was 50% by mass.

By use of a rectangular heater manufactured by Kumagai Riki Kogyo Co.,Ltd., the pulp fiber 24 and the chemical fiber 25 were formed on a wire(trade name: LL-70E (double-woven)) manufactured by Nippon Filcon Co.,Ltd. through a wet forming method. Thereby, a first web 31 was obtained.Subsequently, the ingredient fibers were entangled to each other byapplying a high-pressure water jetting treatment to the two sides of thefirst web 31 with an energy set at 0.38 kW/m² for four times.Thereafter, the first web 31 was dried by use of a rotary drier at atemperature of 120° C. for 3 minutes. By this, a first treated web 33with a basis weight of 16.2 g/m² was made. Incidentally, the pore sizeof the nozzle was 95 μm, and the pores were arrayed at intervals of 0.5mm in the cross direction CD.

(Forming of Second Fiber Layer)

A material slurry obtained by blending NBKP (with a CSF of 600 cc) andLBKP (hardwood chemical pulp) together was used for the pulp fiber 24 ofthe second fiber layer. The proportion of the NBKP (with a CSF of 600cc) in the blended material slurry was 50% whereas the proportion of theLBKP in the blended material slurry was 50%. Thereby, a second web 41was formed through a cylinder paper forming process in a way that thedry basis weight of the second web 41 was 20.4 g/m². Incidentally, thechemical fiber 25 content of the second fiber layer was 0% by mass.

The transferred first treated web 33 and the second web 41 were pressedtogether, and were thus integrated into a wet two-layered laminatewrapping sheet. After drying through dehydration, a two-layered laminatewrapping sheet 70 with a basis weight of 36.8 g/m² was obtained. Thewrapping sheet thus obtained is referred to as “example 1.”

[Measurement of Dry Strength]

By use of a test instrument Tensilon (trade name; manufactured by A&DCo., Ltd.), the dry strength of example 1 was measured with a conditionthat the width of the sample piece was 25 mm; the length thereof was 150mm; the chuck interval thereof was 100 mm; and the tensile speed thereofwas 100 mm/min. The dry strength of example 1 was measured both in themachine direction MD and the cross direction CD. Incidentally, the drystrength thereof means the maximum dry tensile strength of thereof.

[Measurement of Wet Strength]

Example 1 was left to stand still in a closed top container withion-exchanged water being impregnated into example 1 with a moisturecontent of example 1 (or the weight ratio of moisture to the basefabric) being 300% for three hours. Thereafter, by use of the testinstrument Tensilon (trade name; manufactured by A&D Co., Ltd.), the wetstrength of example 1 was measured with a condition that the width ofthe sample piece was 25 mm; the length thereof was 150 mm; the chuckinterval thereof was 100 mm; and the tensile speed thereof was 100mm/min. The wet strength of example 1 was measured both in the machinedirection MD and the cross direction CD. Incidentally, the wet strengththereof means the maximum wet tensile strength thereof.

[Measurement of Dust Permeation]

3 mg of test dust was placed on example 1, which was placed on a pieceof filter paper, for each of the three particle sizes of the test dust.Subsequently, each 3 mg of test dust was suctioned by an aspirator fromunder the filter paper for 30 seconds. Thereafter, how much of the testdust was adhered to the piece of filter paper after permeating example 1was visually evaluated for each particle size of the test dust. A resultof the visual evaluation is shown in Table 1: a case no test dustadhered to the filter paper is indicated by a circle; a case where aminute amount of test dust permeated the example to adhere to the filterpaper but did not fall even when the filter paper was turned upside downis indicated by a triangle; and a case where some test dust adhered tothe filter paper and fell when the filter paper was turned upside downis indicated by a cross.

[Measurement of Air-flow Resistance]

The air-flow resistance of example 1 was measured with a measuringinstrument (trade name: KES-F8, manufactured by Kato Tech Co., Ltd.)with the cylinder-side part of example 1 being put downward. An averageof five measurements of the air-flow resistance of example 1 is shown inTable 1.

[Fluff Test and Measurement]

How much example 1 fluffed was measured by adhering a mold-release-sidesurface of a piece of fabric tape to the friction surface of a rubbingtester for color fastness (manufactured by Daiei Kagaku Seiki MFG. Co.,Ltd.) on example 1, the sample piece having a width of 300 mm and alength of 200 mm. The piece of fabric tape was reciprocated for fivetimes while applying a load of 200 g to example 1: A result of thefluffing test is shown in Table 1: a case where an example did not fluffis indicated by a circle; a case where an example partially fluffed alittle, but no ingredient fiber peeled off, is indicated by a triangle;and a case where an example fluffed overall, and/or ingredient fiberspeeled off, is indicated by a cross.

[Measurement of Hydrolytic Property by Use of Shake Flask Method]

First of all, 800 cc of distilled water was poured into a 1000-ml flask.Subsequently, a squared piece of example 1 with a size of 10 cm×10 cmwas placed in the distilled water. Thereafter, the squared piece ofexample in the distilled water was shaken with a shaker (trade name:SHKV-200, manufactured by IWAKI Co. Ltd.) at a shaking speed of 240 rpmfor 30 minutes. A result of measuring the hydrolytic property thereof isshown in Table 1: a case where an example was so dispersed in thedistilled water that no trace of its original form remained or even thelargest remaining piece of the example became 50 cm² or less in size areindicated by a circle; a case where an example was so dispersed in thedistilled water that the largest remaining piece of the example wasstill more than 50 cm² in size is indicated by a triangle; and a casewhere an example was not dispersed in the distilled water so that theoriginal form of the example remained is indicated by a cross.

In addition to the wrapping sheet according to example 1, wrappingsheets according to examples 2 to 6 were made by adding a dye and asizing agent to each wrapping sheet to such an extent that thehydrolytic property of each wrapping sheet was maintained, and bychanging the pulp fiber 24 content, the chemical fiber 25 content, thebasis weight and the like from one wrapping to another. Subsequently,the properties of each of the wrapping sheets according to examples 2 to6 were tested or measured in the same manner as the properties of thewrapping sheet according to example 1. Incidentally, the wrapping sheetsaccording to examples 2 to 6 were the same size as the wrapping sheetaccording to example 1, and were shaped the same as the wrapping sheetaccording to example 1.

[Forming of Three-layered Wrapping Sheet]

[Forming of First Fiber Layer]

NBKP (with a CSF of 720 cc) and a synthetic pulp (trade name: SWP E-400,manufactured by Mitsui Chemicals, Inc.) were mixedly used as the pulpfiber 24 of the first fiber layer.

Rayon fiber (trade name: Corona, manufactured by Daiwabo Rayon Co.,Ltd.) with a fineness of 1.1 dtex and with an average fiber length of 7mm was used as the chemical fiber 25 of the first fiber layer.

The pulp fiber 24 content of the first fiber layer was 60% by mass (fordetail, the NBKP (with a CFS of 750 cc) content of the first fiber layerwas 50% by mass, and the synthetic pulp content of the first fiber layerwas 10% by mass, where the synthetic pulp was SWP E-400 (trade name)manufactured by Mitsui Chemicals, Inc.). On the other hand, the chemicalfiber 25 content of the first fiber layer was 40% by mass.

By use of the rectangular heater manufactured by Kumagai Riki Kogyo Co.,Ltd., the pulp fiber 24 and the chemical fiber 25 were formed on thewire (trade name: LL-70E (double-woven)) manufactured by Nippon FilconCo., Ltd. through a wet forming process. Thereby, a first web 31 wasobtained. Subsequently, the ingredient fibers were entangled to eachother by applying a high-pressure water jetting treatment to the twosides of the first web 31 with an energy set at 0.38 kW/m² four times.Thereafter, the first web 31 was dried by use of the rotary drier at atemperature of 120° C. for 3 minutes. By this, a first treated web 33with a basis weight of 16.4 g/m² was made. Incidentally, the pore sizeof the nozzle was 95 μm, and the pores were arrayed at intervals of 0.5mm in the cross direction CD.

(Forming of Second Fiber Layer)

A material slurry obtained by blending NBKP (with a CSF of 600 cc) andLBKP together was used for the pulp fiber 24 of the second fiber layer22. The proportion of the NBKP (with a CSF of 600 cc) in the blendedmaterial slurry was 50% whereas the proportion of the LBKP in theblended material slurry was 50%. Thereby, a second web 41 was formedthrough a cylinder paper forming process in a way that the dry basisweight of the second web 41 was 20.4 g/m². Incidentally, the chemicalfiber 25 content of the second fiber layer was 0% by mass.

(Forming of Third Fiber Layer)

NBKP (with a CSF of 720 cc) and a synthetic pulp (trade name: SWP E-400,manufactured by Mitsui Chemicals, Inc.) were mixedly used as the pulpfiber 24 of the third fiber layer 23.

Rayon fiber (trade name: Corona, manufactured by Daiwabo Rayon Co.,Ltd.) with a fineness of 1.1 dtex and with an average fiber length of 7mm was used as the chemical fiber 25 of the third fiber layer.

The pulp fiber 24 content of the third fiber layer 23 was 60% by mass(for detail, the NBKP (with a CFS of 750 cc) content of the first thirdlayer was 50% by mass, and the synthetic pulp (trade name: SWP E-400,manufactured by Mitsui Chemicals, Inc) content of the first fiber layerwas 10% by mass). On the other hand, the chemical fiber 25 content ofthe first fiber layer was 40% by mass.

By use of the rectangular heater manufactured by Kumagai Riki Kogyo Co.,Ltd., the pulp fiber 24 and the chemical fiber 25 were formed on thewire (trade name: LL-70E (double-woven)) manufactured by Nippon FilconCo., Ltd. through a wet forming process. Thereby, a third web 51 wasobtained. Subsequently, the ingredient fibers were entangled to eachother by applying a high-pressure water jetting treatment to the twosides of the third web 51 with an energy set at 0.38 kW/m² four times.Thereafter, the third web 51 was dried by use of the rotary drier at atemperature of 120° C. for 3 minutes. By this, a third treated web 53with a basis weight of 16.4 g/m² was made. Incidentally, the pore sizeof the nozzle was 95 μm, and the pores were arrayed at intervals of 0.5mm in the cross direction CD.

The transferred first treated web 33 was put on the second web 41, andthe third processed web 53 is subsequently put on the resultant secondweb 41. Thereby, the first treated web 33, the second web 41 and thethird processed web 53 are pressed together with the three webs beingstacked one on another, and were thus integrated into a wetthree-layered laminate wrapping sheet. After drying through dehydration,a three-layered laminate wrapping sheet 80 with a basis weight of 53.2g/m² was obtained. The wrapping sheet thus obtained is referred to as“example 7.”

Example 7 was measured in the same manner as example 1 was measured interms of the dry strength, the wet strength, the dust permeation, theair-flow resistance, the fluff test and hydrolytic property by the shakeflask method. Incidentally, example 7 was the same size and shape asexample 1.

Wrapping sheets according to comparative examples 1 to 5 were made asfollows, and were subsequently tested and measured in the same manner asthe wrapping sheet according to example 1. Incidentally, the wrappingsheets according to comparative examples 1 to 5 were the same size andshape as the wrapping sheet according to example 1.

Comparative Example 1

Comparative example 1 was made in the same manner as example 1 was,except that the basis weight of the first fiber layer 21 was 21.4 g/m²whereas the basis weight of the second fiber layer 22 was 10 g/m².

Comparative Example 2

Comparative example 2 was made in the same manner as example 1 was,except that the first fiber layer 21 was made by applying nohigh-pressure water jetting treatment, and except that the basis weightof the second fiber layer 22 was 20 g/m².

Comparative Example 3

Comparative example 3 was made in the same manner as example 1 was,except that the basis weight of the first fiber layer 21 was 32.5 g/m²whereas the basis weight of the second fiber layer 22 was 31.3 g/m².

Comparative Example 4

Comparative Example 4 was made in the same manner as example 1 was made,except that comparative example 4 was a single-layered wrapping sheetmade as follows. For the pulp fiber 24 of comparative example 4, a fibermaterial was made by blending NBKP (with a CSF of 720 cc) and rayonfiber (trade name: Corona, manufactured by Daiwabo Rayon Co., Ltd.) witha fineness of 1.1 dtex and with an average fiber length of 7 mm. Theproportion of the NBKP in the blended fiber material was 50% by mass,and the proportion of the rayon fiber in the blended fiber material was50% by mass. A cationic dye (CI. Direct Red 81, trade name: SumilightRed 4B, manufactured by Taoka Chemical Co., Ltd.) was added to the fibermaterial and was agitated therein when the NBKP and the rayon fiber wereblended together. Subsequently, a cationic sizing agent (or a cationicstyrene resin) (trade name: Size Pine W-360, manufactured by ArakawaChemical Industries, Ltd.) was added to the resultant fiber material andwas agitated therein. By using the resultant fiber material as amaterial slurry, a first treated web 33 was made with the same method asthe first treated web 33 according to example 1, and was subsequentlydried directly. Thus, the single-layered wrapping sheet which had abasis weight of 30 g/m², and which consisted of the first fiber layer 21only, was made.

Comparative Example 5

Comparative Example 5 was made as the same manner as example 1 was made,except that comparative example 5 was a single-layered wrapping sheetmade as flows. For the pulp fiber 24 of comparative example 5, a fibermaterial was made by blending NBKP (with a CSF of 600 cc) and LBKPtogether. The proportion of the NBKP in the blended fiber material was50% by mass, and the proportion of the LBKP in the blended fibermaterial was 50% by mass. A second web 41 was made of the fiber materialwith the same method as the second web 41 according to example 1, andthereafter was dried directly. Thereby, the single-layered wrappingsheet which had a basis weight of 20.4 g/m², and which consisted of thesecond fiber layer 22 only, was made.

EXAMPLE 1 EXAMPLE 2 EXAMPLE 3 EXAMPLE 4 SECOND SECOND SECOND SECONDFIRST LAYER FIRST LAYER FIRST LAYER FIRST LAYER LAYER (CYL- LAYER (CYL-LAYER (CYL- LAYER (CYL- (SL) INDER) (SL) INDER) (SL) INDER) (SL) INDER)NBKP

720 cc 30% 50% 50% 50% NBKP

600 cc 20% 50% 40% 40% 40% UBKP FPEE 50% 40% 40% 40% RAYON 11

7 mm 50% 40% 40% 40% SYNTHETIC PULP SAP E400 10% 20% 10% 20% 20%SPLITABLE FIBER 33

5 mm 10% CATIONIC DYE sunlight Red 48 0.024%   0.024%   0.024%  CATIONIC DYE

 turquoise SIZING AGENT SIZE PNE W-350  3%  3%  3%  3%  3%  3% BASISWEIGHT g/m² 16.2 20.4 16.1 15.2 16.4 19.1 16.5 16.2 OF EACH LAYER TOTALBASIS g/m² 36.8 31.3 35.5 31.7 WEIGHT THICKNESS mm 0.12 0.09 0.10 0.09DENSITY g/cm³ 0.307 0.348 0.355 0.352 DRY STRNGTH MD 18.91 25.36 29.8928.27 N/25 mm CD 7.95 8.75 10.22 8.16 WET STRENGTH MD 2.67 5.04 6.002.19 N/25 mm CD 1.27 1.51 1.89 1.76 DUST 75 μm-1 mm ◯ ◯ ◯ ◯ PERMEATION15-20 μm ◯ ◯ ◯ ◯ 5 μm ◯ ◯ ◯ ◯ AIRFLOW Kpa · s/m 3.07 6.35 7.25 7.01RESISTANCE VALUE FLUFF ◯ ◯ ◯ ◯ HYDROLIC SHAKE FLASK ◯ ◯ ◯ ◯ PROPERTYMETHOD COMPARATIVE EXAMPLE 5 EXAMPLE 6 EXAMPLE 7 EXAMPLE 1 SECOND SECONDSECOND SECOND FIRST LAYER FIRST LAYER FIRST LAYER THIRD FIRST LAYERLAYER (CYL- LAYER (CYL- LAYER (CYL- LAYER LAYER (CYL- (SL) INDER) (SL)INDER) (SL) INDER) (SL) (SL) INDER) NBKP

720 cc 50% 70% 50% 50% 30% NBKP

600 cc 45% 35% 50% 20% 50% UBKP FPEE 45% 35% 50% 50% RAYON 11

7 mm 50% 30% 40% 40% 50% SYNTHETIC PULP SAP E400 30% 10% 10% SPLITABLEFIBER 33

5 mm 10% CATIONIC DYE sunlight Red 48 0.024%   0.024%   0.024%  CATIONIC DYE

 turquoise 0.22%   SIZING AGENT SIZE PNE W-350  3%  3%  3%  3%  3%  3%BASIS WEIGHT g/m² 14.8 20.0 20.7 19.8 16.4 20.4 16.4 21.4 10.0 OF EACHLAYER TOTAL BASIS g/m² 34.8 40.5 53.2 31.4 WEIGHT THICKNESS mm 0.10 0.110.18 0.12 DENSITY g/cm³ 3.48 0.368 0.296 0.200 DRY STRNGTH MD 34.5840.68 51.32 16.21 N/25 mm CD 14.06 16.60 17.55 5.11 WET STRENGTH MD 2.472.26 8.80 2.09 N/25 mm CD 1.29 1.11 2.93 1.04 DUST 75 μm-1 mm ◯ ◯ ◯ ◯PERMEATION 15-20 μm ◯ ◯ ◯ Δ 5 μm ◯ ◯ ◯ X AIRFLOW Kpa · s/m 6.91 9.235.37 2.95 RESISTANCE VALUE FLUFF ◯ ◯ ◯ Δ HYDROLIC SHAKE FLASK ◯ ◯ Δ ◯PROPERTY METHOD COMPARATIVE COMPARATIVE EXAMPLE 2 EXAMPLE 3 COMPARATIVECOMPARATIVE SECOND SECOND EXAMPLE 4 EXAMPLE 5 FIRST LAYER FIRST LAYERSINGLE SINGLE LAYER (CYL- LAYER (CYL- LAYER LAYER (SL) INDER) (SL)INDER) (SL) (SL) NBKP

720 cc 50% 30% 50% NBKP

600 cc 40% 20% 50% 50% UBKP FPEE 40% 50% 50% RAYON 11

7 mm 40% 50% 50% SYNTHETIC PULP SAP E400 10% 20% SPLITABLE FIBER 33

5 mm CATIONIC DYE sunlight Red 48 0.024%   0.024%   0.024%   CATIONICDYE

 turquoise SIZING AGENT SIZE PNE W-350  3%  3%  3%  3% BASIS WEIGHT g/m²16.1 20.0 32.6 31.3 42.2 30.0 OF EACH LAYER TOTAL BASIS g/m² 36.1 63.842.2 30.0 WEIGHT THICKNESS mm 0.10 0.20 0.15 0.08 DENSITY g/cm³ 0.3610.319 0.287 0.517 DRY STRNGTH MD 13.33 54.10 7.71 41.50 N/25 mm CD 4.7719.20 7.02 13.00 WET STRENGTH MD 1.59 10.17 2.85 0.48 N/25 mm CD 0.664.15 2.82 0.14 DUST 75 μm-1 mm ◯ ◯ X ◯ PERMEATION 15-20 μm ◯ ◯ X ◯ 5 μm◯ ◯ X ◯ AIRFLOW Kpa · s/m 7.63 10.27  0.212 13.79 RESISTANCE VALUE FLUFFX ◯ ◯ ◯ HYDROLIC SHAKE FLASK ◯ X ◯ ◯ PROPERTY METHOD

indicates data missing or illegible when filed

It is learned from Table 1 that examples 1 to 7 exhibited a good dustpermeation, dry strength, wet strength, hydrolytic property.Accordingly, while examples 1 to 7 exhibit those properties, they have acertain degree of strength.

By contrast, some of examples 1 to 5 exhibited an enhanced hydrolyticproperty while exhibiting a degraded dry strength, wet strength and thelike. The others of examples 1 to 5 exhibited an enhanced dry strengthand wet strength while exhibiting a degraded hydrolytic property. Yetsome of examples 1 to 5 exhibited an enhanced hermetic property whileexhibiting a degraded hydrolytic property and lint-free property. Basedon this fact, it is learned that, unlike the present invention,comparative examples 1 to 5 was not capable of enhancing the hermeticproperty and hydrolytic property while having a certain degree ofstrength.

Note that entire content of Japanese Patent Application2007-174934(filed on Jul. 3, 2007)is incorporated herein by reference.

INDUSTRIAL APPLICABILITY

As described above, individual package of absorbent article, wrappingsheet, and method of manufacturing wrapping sheet according to thepresent invention provides an individual package and a wrapping sheetwhich both exhibit a hydrolytic property, a soft tactile impression andappearance, and a high air tightness property which does not allowforeign matters to go in beyond the individual package and the wrappingsheet. In addition, the present invention employs a wet paper-formingand layer-combining process with a paper machine to manufacture wrappingsheets with a laminated structure. Thus, it makes a secondary processunnecessary, and it achieves cost reduction. Therefore, the presentinvention is useful.

1. A wrapping sheet for an absorbent article including at least an absorbent exhibiting a fluid retention property comprising: a first fiber layer formed by application of a high-pressure water jetting treatment, the first fiber layer including pulp fiber and chemical fiber, a pulp fiber content of the first layer being 30% by mass to 70% by mass, a chemical fiber content of the first layer being 70% by mass to 30% by mass, an average fiber length of the chemical fiber being not more than 20 mm; and a second fiber layer arranged by laminating the second fiber layer to the first fiber layer, the second fiber layer including pulp fiber, a pulp fiber content of the second fiber layer being 70% by mass to 100% by mass.
 2. The wrapping sheet according to claim 1, wherein the second fiber layer includes chemical fiber not more than 30% by mass with an average fiber length of 20 mm or less and with a fiber diameter smaller than that of the pulp fiber.
 3. The wrapping sheet according to claim 1, further comprising a third fiber layer formed by application of high-pressure water jetting treatment and arranged by laminating the third fiber layer to one side of the second fiber layer with the first fiber layer laminated to the other side of the second fiber layer, the third fiber layer including pulp fiber and chemical fiber, a pulp fiber content of the third fiber layer being 30% by mass to 70% by mass, a chemical fiber content of the third fiber layer being 70% by mass to 30% by mass, an average fiber length of the chemical fiber being not more than 20 mm.
 4. The wrapping sheet according to claim 1, wherein when a 10 cm×10 cm sample piece of the wrapping sheet placed in 800 cc of distilled water is shaken at a shaking speed of 240 rpm for 30 minutes, the sample piece is so dispersed in the distilled water that a largest remaining piece of wrapping sheet being not more than 50 cm² in size.
 5. The wrapping sheet according to claim 1, wherein a basis weight of the first fiber layer is 10 g/m² to 30 g/m², a basis weight of the second fiber layer is 15 g/m² to 30 g/m², and a basis weight of the wrapping sheet is 25 g/m² to 60 g/m².
 6. The wrapping sheet according to claim 3, wherein a basis weight of the first fiber layer is 10 g/m² to 30 g/m², a basis weight of the second fiber layer is 15 g/m² to 30 g/m², a basic weight of the third fiber layer is 10 g/m² to 30 g/m², and a basis weight of the wrapping sheet is 35 g/m² to 60 g/m².
 7. The wrapping sheet according to claim 1, wherein a pattern is formed in at least one of the first fiber layer and the second fiber layer by changing the basis weight of the first fiber layer and/or the second fiber layer.
 8. The wrapping sheet according to claim 1, wherein at least one of the first fiber layer and the second fiber layer is colored.
 9. The wrapping sheet according to claim 8, wherein a color in which the first fiber layer is colored is different from a color in which the second fiber layer is colored.
 10. The wrapping sheet according to any one of claims 1 to 9, wherein at least one of the first fiber layer, the second fiber layer and the third fiber layer includes a sizing agent, and at least partially exhibits a predetermined water resisting property.
 11. An individual package of an absorbent article, comprising: an absorbent article at least including an absorbent exhibiting a fluid retention property; and a wrapping material wrapping the absorbent article, the wrapping material constituted of the wrapping sheet according to claim
 1. 12. A method of manufacturing a wrapping sheet, comprising the steps of: forming a first fiber layer from pulp fiber and chemical fiber into a web in a wet paper-forming method, and subsequently applying a high-pressure water jetting treatment to at least one side of the fiber web to entangle the pulp fiber and the chemical fiber with each other; forming a second fiber layer from pulp fiber and chemical fiber; and conveying the first fiber layer, subsequently integrally laminating the first fiber layer and the second fiber layer to each other while the second fiber layer remains wet, and thereafter drying the laminated first and second fiber layers.
 13. The method of manufacturing a wrapping sheet according to claim 12, further comprising the steps of: forming a third fiber layer from pulp fiber and chemical fiber into a fiber web in a wet paper-forming method, and subsequently applying a high-pressure water jetting treatment to at least one side of the fiber web to entangle the pulp fiber and chemical fiber with each other; and conveying the first and second fiber layer after integrally laminating the first fiber layer and the second fiber layer to each other with the first and second fiber layers remain wet, subsequently integrally laminating the third fiber layer onto the first and second fiber layers while the third fiber layer remains wet, there after drying the laminated first, second and third fiber layers.
 14. The method of manufacturing a wrapping sheet according to claim 12, wherein in at least one of the step of forming the first fiber layer and the step of forming the third fiber layer, the fiber web is transferred from a fiber layer forming wire to a patterning wire after the fiber web is formed, and subsequently the high-pressure water jetting treatment is applied to the fiber web thus transferred.
 15. The method of manufacturing a wrapping sheet according to claim 12, wherein, for at least one of the first and third fiber layers, the fiber web is formed by a paper-forming method of any one of a tanmo type and a fourdrinier type.
 16. The method of manufacturing a wrapping sheet according to claim 12, wherein the high-pressure water jetting treatment is applied to the fiber web place on a fiber forming wire.
 17. The method of manufacturing a wrapping sheet according to claim 12, wherein for the second fiber layer, the fiber web is formed by a paper-forming method of any one of a cylinder type and a former type. 